1. Field of the Invention
The present invention is directed to an obstacle detection system for a vehicle.
2. Description of the Prior Art
U.S. Pat. No. 5,717,399 discloses an obstacle detection system for vehicle use which utilizes a plurality of electromagnetic antennas for transmitting FM radio waves and receiving reflected radio waves for detection of nearby objects as well as remote objects in order to cover a wide detection range. In view of the known fact that the electromagnetic antenna has only insufficient detection capability for detection of nearby objects, particularly due to its narrow directivity, it is necessary to provide a plurality of the electromagnetic antennas within a single radar module for covering a wide detection angle for the nearby object as contemplated in the above patent, or to add a scanning mechanism to the single electromagnetic antenna for covering the wide detection angle. However, this involves additional and complex circuit configurations or mechanical structures with attendant cost increase for manufacture of the system. Further, when the plurality of the differently oriented electromagnetic antennas are combined into the one radar module for detection of the nearby objects over a wide angular detection zone, the individual antennas have to be activated sequentially to monitor individual areas one by one within the detection zone. However, there is always a problem with this detection method that the nearby object is only detected at the last of the sequence, causing a delay in detection response.